However, the frequency of KRAS and BRAF mutations in ESCCs remains inconclusive because of the limited sample sizes of previous studies.8,15–20 The validity of the pyrosequencing method for detecting KRAS and BRAF mutations was initially demonstrated using colon cancer cell lines and colon cancer tissues harboring KRAS and BRAF mutations. The gene discussed is KRAS; the disease is malignant colon neoplasm.